Long considered primarily passive cells, astrocytes play an active role in stimulating the formation and function of new synapses to shape neural circuits during development. An emerging theme from recent research is that autism and schizophrenia are diseases of synapses, and raises the question whether functional defects in astrocytes could contribute to the pathophysiology of common devastating neurodevelopmental disorders. Here I propose the use of novel techniques for acutely purifying primary human astrocytes in addition to a protocol for generating induced pluripotent stem cell (iPSC) derived astrocytes from suspended neurospheres. The goal of these approaches is to address how astrocyte dysfunction might underlie neurodevelopmental disease. In order to demonstrate the feasibility of this new model system, I will focus on generating astrocytes from iPSCs produced from patients with 22q11 Deletion Syndrome. These individuals suffer from neurodevelopmental delay and are among the highest genetic risks of developing schizophrenia. Among the candidate genes in the chromosomal deletion for 22q11, the astrocyte-enriched enzyme proline dehydrogenase (PRODH) has already proven to be a promising player in neurological dysfunction from knockout studies in mice. My work to produce iPSC-derived astrocytes from 22q11 patients will ask whether patient-derived astrocytes contribute to defects in neuronal health, synaptic formation, and / or synaptic function through either cell autonomous or non-cell autonomous mechanisms. In addition to the findings within 22q11 patient lines, the techniques developed in this proposal offer the opportunity to investigate the role of astrocytes in numerous neurodevelopmental and neuropsychiatric disorders.